Since ink jet recording makes less noise, can employ high speed recording, and can use plain paper as the recording paper, it has been employed for terminal printers, etc., and recently has been increasingly used for various purposes. Also, multicolor recording can be easily performed, e.g., by using multiple ink nozzles, and multicolor ink jet recording by various ink jet recording systems has been investigated.
Among ink jet recording sheets and mediums used for ink jet recording are wood free papers, slip-writing continuous paper webs, art papers, coated papers, low-density papers without size, ink jet recording papers having relatively good ink absorbing property and showing less blotting of ink as described in Japanese Patent Application (OPI) Nos. 53,012/'77, 74,340/'77 and 49,113/'78 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), fabrics, plastic films having ink absorbing surfaces, wood boards, metallic sheets, etc.
Onto such ink jet recording sheets, ink jet recordings are generally formed by application of aqueous inks. Aqueous inks for ink jet recording are typically composed of water-soluble dyes, humectants, dye-solubilizing agents, mold inhibitors, water, and water-miscible organic solvents, as described in Japanese Patent Application (OPI) Nos. 89,534/'74, 97,620/'74, 143,602/'75, 102,407/'75, 129,310/'76, 137,506/'76, 137,505/'76, 115,106/'76, 139,408/'76, 12,008/'77, 12,009/'77, 12,010/'77 and 74,406/'77; Japanese Patent Publication Nos. 14,643/'77 and 14,644/'77; Japanese Patent Application (OPI) Nos. 77,706/'78, 119,107/'78 and 119,108/'78; and Japanese Patent Publication No. 20,882/'78. Examples of the water-soluble dyes include direct dyes, acid dyes, and basic dyes.
Ink jet records obtained by applying conventionally known aqueous inks on the above-described known ink jet recording sheets exhibit the fault that when the records are splashed or wet with water, the records of dyes blot or diffuse completely due to the poor water resistance property thereof. Furthermore, when the records are preserved for a long period of time in a high humidity condition, the ink jet record also blots.
When an ink jet recording paper contains a dyeing component and the amount of jetted ink is small, as in the case of monochromatic ink jet recording, the water resistance properties of the records may be satisfactory for practical purpose if a dye or dyes having good water resistance properties are used. However, in the case of multicolor ink jet recording, the amount of jetted inks is relatively large, and records having sufficient water resistance properties cannot be obtained even when the ink jet recording paper contains good individual dye components. When papers recorded by ink jet printing are used, for example, for outdoor notifications or advertisements, the records are required to have particularly good water resistance properties but multicolor ink jet records formed by the combination of conventional ink jet recording papers and ink jet recording inks have been utterly unsuitable for such practical use.